Paint and varnish remover containing furfural



Patented Oct. 25, 1932 UNITED STATES PATENT OFFICE BORIS N. LOUGOVOY, OIMON'ICLAIR, NEW JERSEY, ASSIGNOR TO OHAD ELOID CHEMICAL COMPANY, OF NEWYORK, N. Y., A CORPORATION OF WEST VIRGINIA PAINT AND VABNISH REMOVERCONTAINING 'FURFURAL No Drawing.

This invention relates to paint and varnish removers containing furfuraland especially to this solvent incorporated with other sol vents with orwithout a thickening agent and further relates to an incorporation ofthis solvent with certain other solvents, illustratively an alcohol anda chlorinated hydrocarbon in order to'produee a highly e cient paint andvarnish remover having certain characteristics which differentiate fromother paint and varnish removers in several useful respects.

When applied by itself furfural drains off of vertical surfaces and theaction is aggra- 1a vated by the fact that this solvent does not wet thesurface readilybut tends to gather in drops. The addition of anauxiliary or co-operative solvent such as alcohol, benzol, toluol andvarious chlorinated solvents, such as as carbon tertachloride, acetylenetetrachloride,.trichlorethylene and particularly monochlorbenzol maybeused to overcomethe difficulty of lack of,surface wetting, to someextent.

To give body or consistency to the composition a thickener may beincorporated including wax, soap and various other thickeners such asesthers of cellulose in some cases. Wax is especially serviceable torese tard the evaporation of volatile solvents and for this purposeparaffin or ceresin wax (mineral wax) is best. Furfural is slow toevaporate but may be incorporated with more volatile solvents whichrequire repression of evaporation to confine them to the surface to besoftened. The proportion of the wax in fact depends on the nature of thesolvents used but, generally, it is better to employ as little wax aspossible, particularly if the remover is used to clean off a surfacewhich is afterwards to be coated with nitro-cellulose lacquer.

Not all volatile solvents are adapted tobe used with furfural, gasolineand petroleum naphtha of themselves not being miscible and furthermorenot possessing any satisfactory paint and varnish removing qualities. Tosecure good results solvents which are miscible should be chosen or ifan immiscible solvent is. to be included the addition of blend- 1928.Serial No. 286,496.

ing solvents sometimes will bring about miscibility. In general therequirements of a paint and varnish remover of a commercial characternecessitate the employment of solvents of strong cutting qualities andthe addition of substantial proportions of indifferent solvents tends toproduce a low grade remover of unsatisfactory qualities incapable ofreaching commercial standards.

The speed of a commercial remover, that is, the shortness of timerequired to soften the coat of paint or varnish, 1s very essential froma n-actical standpoint because a fast powerful the removal of the paintfrom a given surface but also will save some expense in the consum )tionof materials.

T e activity of a paint and varnish remover is usually tested in thetrade by a means which is not absolutely reliable but nevertheless isregarded sufficiently convincing to the user. The method involves theapplication of some of the removing composition to a surface coated witha paint or varnish and to note the time taken for the surface towrinkle. This wrinkling effect is regarded as an indication of thesolvent action or cutting power of the removing composition.

The method adopted when working on the present problem to determine thecutting power was as follows: A piece of old painted wood was selected,taking care that the portion used had a good even, thick coat of aint.This was cut into strips. Various so vents were placed in a series oftest tubes and a strip of the ainted Wood was put into each test tube.be time which ela ised before the first appearance of any wrink ing wasaccurately noted for each solvent. by means of a stop watch. Thecomparative removing action or cutting power was thus roughlyrepresented by the number of elapsed seconds.

Solvent mixtures vary greatly in cutting power. In removers involvingthe use ofa penetrating hydrocarbon such as benzol and a looseningsolvent of an alcoholic or ltctonio remover not only will save time invnature a very great variation is observable in the cutting actiondepending uponthe solvents employed.

In regard to removing action furfural by itself has relatively only milddissolving power and as already stated possesses the dis advanta e ofdraining off of verticalsurfaces.

In addition, I have observed that furfural in most mixtures with" othersolvents also ossesses the rather undesirable roperty of slow initialaction, that is, w en applied to a painted surface the mixture acts veryslow at the beginning in comparison wit non-furfural mixtures with otherloosenin solvents. On the other hand when furfura is used, and thecutting action starts, it progresses rapidly. .In order to roduce aremover with a high speed of initlal attack I find it necessary tocorrect this peculiar disadvantage of furfural.

'In the course of my investigations on paint and varnish removers, Idiscovered that a combination of furfural, monochlorbenzol and anhydrousmethyl alcohol is surprisingly advantageous. I A combination of thosethree solvents produces a very fast-acting removing composition. I alsoobserved that as soon as either-one of the, above three ingredients wasomitted fromthe mixture and re laced with some other solvent, even of asimilar character, the activity or efilciency of the remover immediatelydropped in greater or lesser degree. 4 i

In an efiort to secure the quickest possible action for a paint andvarnish remover I proceeded first with the investi ations of the cuttingpower of various sing e solvents of diflerent nature's, turnin them to amixture of two solvents, three so vents, and so forth.

In this investigation many interesting facts have been observed whichare illustrated in I the tabulation below in connection with thefurfural-containing compositions, the tests being conducted on paintedstrips as de-' scribed above:

In the above mixtures ofvar'ious solvents equal volumes of eachcomponent solvent are used in all cases. L

an oilpaint) was utilized.

have a practical value in assures,

Throughout this present description the terms methanol and "methylalcohol are used in a synonymous manner, and the tests herein all referto the anhydrous material, in order to be comparative. Anhydrous. 3methanol is superior to the product containing 5 to 10% or so of water.

The term ,meth l solvent as hereinafter employed is inten ed to embracemath 1 alcohol and meth l acetate, which as s own in the above Ta le 1,are both highly effective in removers of the present invention.

It is understood that all formulas given below should be regarded onlyas exam Ice and that I do not wish to restrict mysel to the exactroportions given in these formulas. All t 'ese examples will include inthe formulas parafiin wax as an agent to retard evaporation of thesolvents for comparison (but without restricting the invention; and insome cases will also include nitrocel ulose (scrap celluloid as an agentto increase the consistency of t e paintand varnish remover. It shouldbe noted in this connection that the addition of various solids whichare capable of dissolving in one of the solvents used in paint andvarnish remover generally will result in cutting down of the s eed of agiven solvent or of a mixture of t is solvent with other solvents, andtherefore the cutting speed or rate of attack of wax-containingcompositionswill be slower than the cutting speed of a correspondinmixture without a wax. The figures in Ta 1e 2, which refer tocomposition of removers, re resent the f amount of each ingredient b voume includ ing wax (which is re orte as measured in the, molten state).Ta le 2 sets forth the cutting speed of each composition in the numberlag of seconds necessary to produce wrinkling of a given paintedsurface. For this purpose a part of an old automobile finished with achremover was placed on the surface in approximately the same quantity andthe time was noted by means of a stop watch when the blistering orwrinkling of the surface was plainly observable.

In order that a paint and varnish remover j,.. addition to its sill cienor powerto penetrate the paint it shou d also possess the property ofremaining wet fora long eriod. The retardation of evaporation, as a'lally accomplished by introducing into the removing ,com osition acertain amount of wax or other m-iorming substance. However, therelative amount of such agent is lim=' ited due to the fact, which hasalready been mentioned, that any solid substances intrc= dueed into theremover generally will de crease its activity. The, rate of evaporationof paint and-varnishremovers in part depends not only upon the relativeamount of e material used to arrest evaporation, but also a readymentioned, is usu= memes 3 in a large degree upon the boiling point andvapor pressure of solvents included in the remover. The boiling point ofeach individual solvent is of importance as well as the ratio betweenthe boiling point and/or the vapor pressure of wax solvent to theboiling point and/or the vapor pressure of wax precipitant. As a generalrule the wax precipitant should be the less volatile body.

From the standpoint of rate of evaporation a remover welcome forpractical use will be one which loses not over about 5% of its Weightin, say, twenty-four hours. iemover applied in the afternoon then willbe found on the following morning to have penetrated even very obstinatecoatings and to have softened or j ellified them for ready removal withwire brush or )utty knife.

Data regarding loss. in weight of the furfural-containing removerstherefore are included in Table 2.

Table :2.-0o1apoaltton 01 typical removers (parts all by volume)Solvents 1 2 8 4 B 6 7 8 12 18 14 Dlohlorben Monoohlorbenzol. 40......40 40 40 .40 40 enzol. 40 40... Furfural 20 20 20 20 20 20... 2O 25 b0Methanol 20 20 20..'.... 20 20 2e 20 2d... Acetone 2t) 20... 20 20 1b.Lugosol ......i 20... Methyl acetate... 20 20 20 20 20... 20 1b 20"..."

ex ..22222223 224 Trlehlorethylenm 40 60 Comparative cutting speed inseconds anm uso 55 130120 100 120360 Lorain welahtln 241mm!(%)....l.43.2t.8 44.15.5100 32 2612.fi- 1 Examination of the abovetableshows that in order to secure the fastest acting composi- I tions it isnecessary to use all three solvents,

viz: monochlorbenzol, furfural and anhydrous methanol simultaneousl Theaddition of some other solvent of eit er ketonic or esteric nature willonly increase the absolute value of the gcmoving power within acomparatively narrow limit. Example 1, representing a combination givingthe fastest remover, includes methyl acetate in addition to the abovethree basic solvents. Replacement of methyl acetate with acetone,.as inExample 6, causes the absolute speed of the remover to drop slightly butthe composition will still remain faster than any other composition fromwhich one of the three basic solvents has been omitted, as for instancecompositions in Examples 4 and 7. The other mixtures are grouped asfollows: Examples 2 and 3 represent mixtures in which monochlorbenzol isomitted. Examples 4 and 5 represent mixtures in which anhydrous methanolis omittedf Examples 7, 8 and 9 represent mixtures inwhich furfural isomitted and Examples 1, 6, 10 andll represent mixtures containing allthree basic solvents together.

These figures are by no means absolute but serve to indicate in ageneralway the advantages of using with furfural a solvent of themonochlorbenzol type in conjunction with a methanolic solvent yielding aremover possessin high initial surface wrinkling power capab e ofrapidly opening the surface to the ingress of solvent. Such a removeroffers a considerable saving in time in the cleaning off of paintedsurfaces, especially those where by the efiect of long exposure to theair, the outer layer of the coating is oxidized to a state of highresistivity to solvent action.

While Ihave found anhydrous methyl alcohol to be the most advantageousco-operating solvent with furi'ural es ecially as a potentsurface-opening agent, i do not limit myself to this surface-openingactivator but may include other highly volatile solvents containing themethyl group such as methyl acetate and the like.

What I claim is 1. A high speed paint and varnish remover possessinghigh initial surface wrinkling ower capable of rapidly opening thesurace to ingress of solvent, sald remover containin furfural, methanol,chlorinated hydrocar ons miscible therewith, and a wax.

2. A high speed paint and varnish remover possessing hlgh initialsurface wrinkling power capable of rapidly opening the surface toingress of solvent, said remover com rising .furfural, monochlorbenzol,anhy rous 5. A high speed paint and varnish remover I possessing highinitial surface wrinkling power capable of rapidl opening the surface toingress of solvent. sai remover containing furfural, a wax solventselected from the roup consistin of benzol, toluol and chlor: enzol,methyl a cohol, and a wax.

6. A finish remover comprising furfural a methyl solvent selected fromthe herein escribed group consisting of math 1 alcohol and met ylacetate an aromatic c lorinated single ring hydrocarbon wax solvent, anda wax. r 7. A finish remover comprising furfural and anhydrous methylalcohol.

8. A finish remover com rising furfural and a highly volatile methysolvent selected 1 from the herein described group consisting of methylalcohol and methyl'acetate, a wax solvent and wax. Y

9. A high speed paint and varnish remover possessing .high mitialsurface wrinkling power capable of rapidly opening the surface toingress of solvent said remover contain ing furfural, a benzoiic solventselected from the group consisting of benzol and chlorben- V sur ace toingress of solvent, said remover containing furfural, a benzolic solventselected from the group consisting of benzol and chlorbenzol, methylacetate, and a small percentage of a wax.

BORIS N. LOUGOVOY aint and varnish re-

